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Multidisciplinary Design Optimization of a Composite Amphibious Aircraft Fuselage Plamen Roglev, MSc. Perun TM EOOD P.O.Box 26, 4001 Plovdiv, BULGARIA.

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Presentation on theme: "Multidisciplinary Design Optimization of a Composite Amphibious Aircraft Fuselage Plamen Roglev, MSc. Perun TM EOOD P.O.Box 26, 4001 Plovdiv, BULGARIA."— Presentation transcript:

1 Multidisciplinary Design Optimization of a Composite Amphibious Aircraft Fuselage Plamen Roglev, MSc. Perun TM EOOD P.O.Box 26, 4001 Plovdiv, BULGARIA

2 The golden age of seaplanes is long gone… because of: Higher weight Higher weight Higher drag Higher drag Corrosion Corrosion

3 Power-to-weight ratio of planing boats and airplanes

4 Empty weight to Maximum take-off weight of commercial seaplanes and landplanes

5 Empty weight to Maximum take-off weight of LSA seaplanes and landplanes

6 Advantages of composite structures for amphibious aircraft Eliminate corrosion Eliminate corrosion Reduce weight Reduce weight Cheaper maintenance and longer life Cheaper maintenance and longer life Improved shape – lower drag Improved shape – lower drag

7 Sandwich structures -lighter, because they are stiffer -cost-effective -can be more damage tolerant -provide flotation Single Skin Laminate- Blunt Projectile Damage Sandwich Laminate- Blunt Projectile Damage Photo by High Modulus (NZ) Ltd.

8 Application of the progress in planing boats design Optimization of planing hullforms Resistance Resistance Longitudinal and lateral stability Longitudinal and lateral stability Experience with composite hull structures Design Design Usage Usage

9 Amphibious aircraft design is multidisciplinary by nature – there are contradicting requirements for aerodynamics, structural performance and hydrodynamic properties : Planing Stable Take-off – low drag and spray, longitudinal stability – porpoising Stable Take-off – low drag and spray, longitudinal stability – porpoising Hull loads during take-off and landing Hull loads during take-off and landing Displacement regime Seaworthines – hull volume Seaworthines – hull volume Lateral stability Lateral stability

10 Traditional design of seaplanes Use of semi-empirical equations based on statistical data Use of semi-empirical equations based on statistical data Data obtained from model scale tests Data obtained from model scale tests Experience from former projects Experience from former projects Sequential determination of design parameters Sequential determination of design parameters To explore new designs physics based models should be introduced

11 Challenges for the high-fidelity CAD based analysis methods(Navier-Stokes fluid flow and FEM structural analyses) High complexity of the flow High complexity of the flow Very high computational cost Very high computational cost Numerical noise due to discretization Numerical noise due to discretization Impossible to explore large design spaces Impossible to explore large design spaces The solution: Use metamodels (models of models) for MDO

12 Benefits of metamodels: Merging of data from simulation and experimental analysis Merging of data from simulation and experimental analysis Filtering of numerical noise and experimental errors Filtering of numerical noise and experimental errors Low computational cost – rapid exploration of the design space Low computational cost – rapid exploration of the design space Possible to use gradient-based optimization methods Possible to use gradient-based optimization methods Visualization of the dependencies Visualization of the dependencies

13 Flying boat hull definitions Beam load coefficient Beam load coefficient Displacement Froude Number Displacement Froude Number

14 Comparison of the hull resistance of planing boats and hydroplanes

15 Flying boat design is determined by the take-off condition Most important parameter - beam Classic approach – empirical Classic approach – empiricalMunro[2] Δ – weight [kg] b- beam [m]

16 Application of planing boats data: Diehl[1] Determination of beam from the hydrodynamic lift coefficient Beam K=K(β, Clmax) S – wing surface

17 Determination of beam for lateral stability in planing bmin (β, Δ)[m] = 0,5 + 0,0004 Δ[kg]-0,55 β[rad] Longitudinal stability in planing Forebody length/beam>3 Seaworthiness requirements Hull volume>3*displacement

18 MDO methodology Create physics based metamodels for the drag and weight of a seaplane hull as functions of length to beam ratio and deadrise angle Create physics based metamodels for the drag and weight of a seaplane hull as functions of length to beam ratio and deadrise angle Determine the constraints from the hull volume requirements and the necessary forebody length Determine the constraints from the hull volume requirements and the necessary forebody length Calculate the design pressures(CS-23) Calculate the design pressures(CS-23) Build a Pareto front and select the design parameters according to mission and seaworthiness requirements. Build a Pareto front and select the design parameters according to mission and seaworthiness requirements.

19 Response surfaces Weight / min weight (L/b, βº) Weight / min weight (L/b, βº) Constant volume of hull Constant volume of hull Cx / Cxmin (L/b, βº) Cx / Cxmin (L/b, βº)

20 Pareto front Drag-Weight tradeoff Drag Weight

21 Design Study – Composite amphibious aircraft investigation The benefits from replacing the Al alloy structure with CFRP sandwich one and optimizing the geometry of the planing hull

22 Future Work Improve the metamodels with application of kriging or radial basis functions Improve the metamodels with application of kriging or radial basis functions

23 References 1.Diehl, W. – The application of basic data on planing surfaces to the design of flying- boat hulls, NACA rep No 696, Munro, W. – Проектирование и расчет гидросамолетов – Москва 1935


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